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参数资料
| 型号： | MIC28500 2A EV |
| 厂商： | Micrel Inc |
| 文件页数： | 17/29页 |
| 文件大小： | 0K |
| 描述： | BOARD EVAL FOR MIC28500 2A |
| 标准包装： | 1 |
| 系列： | Hyper Speed Control™，SuperSwitcher II™ |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 12V |
| 电流 - 输出： | 2A |
| 输入电压： | 30 ~ 75V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 250kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | MIC28500 |
| 其它名称： | 576-4019 |
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Micrel, Inc.
Application Information
Setting the Switching Frequency
The MIC28500 is an adjustable-frequency, synchronous
buck regulator featuring a unique digitally modified
adaptive on-time control architecture. The switching
frequency can be adjusted between 100kHz and 500kHz
by changing the resistor divider connected network
consisting of R18 and R19.
MIC28500
programmed to either lower end or higher end, the
design needs optimization.
Inductor Selection
Values for inductance, peak, and RMS currents are
required to select the output inductor. The input and
output voltages and the inductance value determine the
peak-to-peak inductor ripple current. Generally, higher
inductance values are used with higher input voltages.
Larger peak-to-peak ripple currents will increase the
power dissipation in the inductor and MOSFETs. Larger
output ripple currents will also require more output
capacitance to smooth out the larger ripple current.
Smaller peak-to-peak ripple currents require a larger
inductance value and therefore a larger and more
expensive inductor. A good compromise between size,
loss and cost is to set the inductor ripple current to be
equal to 20% of the maximum output current. The
inductance value is calculated by Equation 3:
Figure 5. Switching Frequency Adjustment
The following formula gives the estimated switching
frequency:
L =
V OUT × (V IN(max) ? V OUT )
V IN(max) × f sw × 20% × I OUT(max)
Eq. 3
f SW _ ADJ = f O ×
R 19
R 18 + R 19
Eq. 2
where:
Where f O = Switching Frequency when R18 is 100k and
R19 being open, f O should be typically 500kHz. For more
precise setting, it is recommended to use the following
graph.
f SW = switching frequency, 300kHz
20% = ratio of AC ripple current to DC output current
V IN(max) = maximum power stage input voltage
The peak-to-peak inductor current ripple is:
500
Switching Frequency
Δ I L(pp) =
V OUT × (V IN(max) ? V OUT )
V IN(max) × f sw × L
Eq. 4
450
R18 = 100k, I OUT =1A
400
350
300
250
VIN = 48V
VIN = 75V
The peak inductor current is equal to the average output
current plus one half of the peak-to-peak inductor current
ripple.
200
150
I L(pk) =I OUT(max) + 0.5 × Δ I L(pp)
Eq. 5
100
50
0
The RMS inductor current is used to calculate the I 2 R
losses in the inductor.
10.00
100.00
1000.00
10000.00
I L(RMS) = I OUT(max) +
R19 (k Ohm)
2
Δ I L(PP)
12
2
Eq. 6
Figure 6. Switching Frequency vs. R19
The evaluation board design is optimized for a switching
frequency of 250kHz. If the switching frequency is
Maximizing efficiency requires the proper selection of
core material and minimizing the winding resistance. The
June 2011
17
M9999-060311-B
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相关代理商/技术参数 |
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| MIC28500YJL TR | 功能描述:直流/直流开关调节器 75V/4A DC-DC Buck Regulator with HSC RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
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| MIC28500YJL-TR | 功能描述:Buck Switching Regulator IC Positive Adjustable 0.8V 1 Output 4A 28-PowerVQFN Variant, 28-MLF? 制造商:microchip technology 系列:Hyper Speed Control?，SuperSwitcher II? 包装:剪切带（CT） 零件状态:过期 功能:降压 输出配置:正 拓扑:降压 输出类型:可调式 输出数:1 电压 - 输入（最小值）:30V 电压 - 输入（最大值）:75V 电压 - 输出（最小值/固定）:0.8V 电压 - 输出（最大值）:61.5V 电流 - 输出:4A 频率 - 开关:100kHz ~ 500kHz 同步整流器:是 工作温度:-40°C ~ 125°C （TJ） 安装类型:表面贴装 封装/外壳:28-PowerVQFN 变式，28-MLF? 供应商器件封装:28-MLF?（5x6） 标准包装:1 |
| MIC28510 12V EV | 功能描述:电源管理IC开发工具 75V/4A DC-DC Buck Regulator with HSC - Evaluation Board RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MIC28510 5V EV | 功能描述:电源管理IC开发工具 75V/4A DC-DC Buck Regulator with HSC - Evaluation Board RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
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